126 
GEOLOGY OF THE FIRST DISTRICT. 
Some boulders were observed on and among the sands of this formation, near the railroad 
from Albany to Schenectady ; but they were not examined minutely, and perhaps belong to 
the subjacent drift deposits, which may here emerge through the sands and clays of this 
formation. 
In some localities, the sand and clay alternate in thin layers, as at Montauk point; where 
the upper portion of the cliff is composed of alternating layers of these substances, from a 
line to an inch thick; while the mass below is composed of loam and clay, intermixed with 
crusts, concretions and geodes of limonite. (Vide Plate 4, fig. 2). The figure referred to is 
not correctly explained on the plate. The masses at that locality are, 
1. Soil and sand; 
2. Sand and clay in thin layers; 
3. Loam and clay with iron crusts, etc.; 
4. Hardpan of drift, cemented by clay, to the ocean level. 
Springs flow from the junction of 3 and 4. 
The gravel and pebble beds of the quaternary formation of the Hudson valley are composed 
of washed fragments of all the various rocks in the vicinity, in such directions that currents 
flowing from a northwardly course would sweep them down the neighboring valleys. 
The grey or buff-colored clay of the quaternary division is usually separated from the over- 
lying sand and gravel beds, by a perfectly defined surface ; but in some instances loam inter¬ 
venes, or clay and sand alternate in thin layers between the main masses. In the valley of 
Lake Champlain and the Hudson, the upper clay bed is almost always grey or buff, striped 
with slightly varied colors, very uniform in its appearance and chemical composition, contain¬ 
ing carbonate of lime sufficient to effervesce with acids, and to justify Professor Eaton’s name 
of marly clay. The blue clay is also as well marked and uniform in its characters, through 
the extensive district referred to, as the grey clay, and the division between them is usually 
a well defined surface. This clay also contains lime, and its blue color seems due to its 
having been formed from the dark-colored slates and limestones of that region. The upper 
clays and sands of Long island, and even those of Staten island, and the lower part of the 
Hudson below Sing-Sing, which were mostly derived from other rocks than those above Sing- 
Sing, have a different color and composition, though apparently of equivalent age.* 
Dr. Samuel L. Mitchill mentioned the clay beds of this series in his Mineralogical History 
of New-York, in his report as Commissioner of the Society for promoting agriculture, arts 
and manufactures, in the year 1800. He says, “The flat between the basaltic rocks and 
Stony point at Haverstraw appears to be Avholly underlaid by argillaceous strata, which, as 
their edges appear along the shore, are not yet hardened enough to withstand the impression 
of the walker’s foot. Much of the level country between Redhook and Greenbush is evidently 
♦ The clay beds in the valley of the Schoharie creek have the same characters as those of the Hudson river, while those of the 
Delaware and Susquehannah are entirely different. 
